Small guns for perforating casing



June 18, 1957 G. F. ABENDROTH SMALL GUNS FoR PERFORMING CASING Filed Sept. l1. 1950 TUBIN G TUBING ELECTRICAL GASING CABLE PRODUCTIUN ZONE FIS.

DEVIL MsAsuRme LINE BATTERY AND SWITGH MAGNET INVENToR. Guss E Abendfofh,

ATTORNEY.

United States Patent SMALL GUNS FR PERFRATNG CASING Guss F. Abendroth, Houston, Tex., assigner, by mesne assignments, to Esso Research and Engineering Conrpany, Elizabeth, N. J., a corporation of Delaware ppiication September 11, 1950, Serial No. 184,163

2 Claims. (Cl. lill-1.8)

This invention relates to guns for perforating pipe in oil wells or the Alike and more particularly to guns which are small enough to run through tubing in a well for perforating casing beneath the tubing.

Guns and explosives have long been used for perforating casing in oil wells and the art is well developed. As commonly constructed the barrels of guns used for such purposes approach in length, as far as is practical, the diameter of the casing so as to obtain the maximum re power. Even under the best conditions, efective`pe1'foration of oil well casing and the cement which usually surrounds it, is difficult to accomplish, and since the size of the gun or explosive is important, casing perforators as conventionally used have not been run into the Well through tubing or other pipe smal-ler in diameter than the casing.

It has recently been proposed to .perform certain operations including the perforating of casing in an oil well while tubing is in it. See for example application of Theodore A. Huber, Serial No. 133,025, filed December 15, 1949, for Method of Completing and Repairing Oil Wells where the use of a casing perforating gun capable of being run through tubing is required. Large savings in time and cost can be effected in this way if effective perforation can be accomplished.

In accordance with application Serial No. 184,161, led by Theodore A. Huber, now Patent No. 2,639,770, it is proposed to solve the problem of providing effective firing power to perforate casing with an assembly which is run into and out of the well through tubing by arranging the guns in their carriage on trunnions and by providing means for rotating them from the vertical positions which they occupy while being lowered into the well, into horizontal tiring positions. inasmuch as the guns may be red by electricity, Huber proposed to employ an electric motor to rotate them exactly the right amount.

In accordance with the present invention, it is proposed to mount bullet guns or shaped charges of explosive in xed position in the gun body or carriage, as in conventional designs, but make them and their carriage small enough in diameter to permit the assembly to be lowered into the well through tubing. After it is lowered through the tubing, means is provided for moving the assembly into contact with the casing. The guns or shaped charges are all pointed in the same direction and the positioning means is such as to cause them to re directly into the casing with as little interference as possible from mud or other lluid in the borehole.

The objects of the invention will be apparent from the following description, taken in connection with the accompanying drawings in which:

Fig. 1 is a vertical cross-sectional view of casing and tubing in an oil well with a gun constructed in accordance with the present invention being 'lowered downl through the tubing.

Fig. 2 is a view similar to that of Fig. 1 but showing the gun beneath the tubing and being fired to perforate the casing and surrounding earth formation.

Fig. 3 is a vertical cross-sectional view of casing and tubing in an oil Well with a gun constructed in accordance with .another embodiment of the invention located in the casing.

Fig. 4 is a view similar to that of Fig. 3 with a gun constructed in `accordance with still another embodiment of the invention located inthe casing.

Fig. 5 is a circuit diagram of the gun .shown in Fig. 3.

. Fig. 6 is a circuit diagram of the gun shown in Fig. 4.

Fig. 7 is a fragmentary cross-sectional view showing the mounting of the electromagnet used in the guns of Figs. 3 and 4, and

Fig. 8 is a transverse cross-sectional view of the embodiment of the invention shown in Fig. 3, the view being taken on the line 8 8 thereof.

Referring to the drawing in detail, and first to the embodiment of the invention shown in Figs. l and 2, it will be seen that casing of an oil well is there shown at 12. Tubing 13 is positioned in the Well with -its lower end above the portion of the casing 12 which is to be perforated, as shown in Fig. 2.

Within the tubing 13, as shown in Fig. 1, and beneath the tubing, as shown in Fig. 2, is a gun body or carriage 14 which is lowered into the well Von an electric cable 15. The carriage 14 may be made of steel and is of cylindrical shape and of course smaller `in diameter than that of the tubing.

Perforating guns 16, here shown as ofthe type whichl tire bullets, as mounted in the carriage 1'4 al'l pointing in the same `direction (to the left as viewed in Figs. 1 and 2).

Adrag spring 17 is secured by bolts 18 to the opposite side of the carriage 14. The action ofithisispring is such, as shown in Figs. V1 and 2, as to cause the carriage to move laterally when it cornes out of the bottom of the tubing in the direction the guns A16 -are pointing. This brings the muzzles of the guns -16 into direct ycontact with the casing so that when the bullets 20 are ltired to perforate the-casing 12 `and surrounding formation 21, they will travel through a minimum of -mud or other uid in the well bore. Thus a maximum of penetration is attained for the -size of guns land bullets available in an assembly which can be lowered through the tubing, practically no pav/[er being wasted in driving the bu'llets ythrough 'well The arrangement `of Figs. l 'and 2-has certain .inherent disadvantages. The gun body 14 and `the spring 17 are dragging all during the time that the assembly is being lowered down through the tubing 13 and since the spring 17 is extremely distorted in the tubing and is necessarily strong in order to move the gun body 14 after it passes out of the tubing, the friction is high.

In order to overcome these disadvantages, the embodiments of the invention shown in Figs. 3 to 7 have been devised.

ln Fig. 3, the casing is again shown at 12 and the tubing 13 and the gun body 14 is again lowered down through the tubing on an electric cable 15. In this figure, as well as in Fig. 4, shaped charges of explosives are shown at 22 instead of the bullet guns 16 of Figs. 1 and 2.

In order to causeshaped charges of explosives to direct their jets to perforate casing properly, as is now well known, the charges must be positioned accurately with respect to the casing. The proper distance from the casing is known to those skilled in the art as the standoit distance.

According to the present invention, the shaped charges 22 all point in one direction (to the left in Figs. 3 and 4) and they are so mounted with respect to the outer shell of the carriage 14 as to have the proper stand-olf distance from the casing 12 when the carriage 14 is iu l if Y i 2,796,023

contact with the casing 12 the axes of the jets of the shaped charges as shown in Fig. 8.

To bring about this -exact location of the carriage 14 when the `shaped charges 22 Yare to be'red, velectromagnetsf23 are employed.- These are secured in the gun body 14 as shown in Fig'. 7 being vertically aligned with the shaped charges 22, as shown in Figs. 3 andV 4. Thus when the electromagnets 23 are energized the guns will be brought into proper tiring position, the casing 12 being of -ferrous material and gripped by the magnets.

The magnets 23 should be energized before and during the tiring. Where a cable 15 is used to conduct electric current to the gun for rin/g, it is convenient to employ a circuit like that shown in Fig. 5in which two sources of alternating current, 24 and 25, are located at the surface of lthe groundand connected to the conductor 26 of the cable 15. One source is of a particular frequency, say 500 cycles, which will be transmitted through the band pass filter 27 in the body 14.` The other source is of some other frequency, say 60 cycles, which cannot be passed by the filter 27. The iilter 27 is in series with the fuse or fuses 28 which iire the shaped charges 22. Thus by connecting rst one source (the 60 cycle source in the example given) and then both sources to the conductor 26, the electromagnets 23 (only one of which is shown in Fig. 5) are energized before the guns are fired and they are held energized While the guns are fired.

In Fig. 4, an electric cable 15 is not employed but a small wire measuring line or ordinary cable 29 is used instead. The guns are fired by causing a go-devil 30 to pass down the line 29 and strike a button vswitch 31 located at the top of the carriage 14.

The circuit for this embodiment of the invention is shown in Fig. 6. A battery 32 and a time delay relay switch 33 are located in the carriage 14. When the switch 31 is closed by the go-devil 30, the electromagnets 23 are immediately energized but the fuse or fuses 28 are not energized until the contact of the relay switch 33 is actuated. Hence the magnets 23 have time to move the guns into proper position before they are fired.

It will be apparent that while only a few embodiments of the invention are shown and -described herein, various changes may be made without departing from the spirit of the invention or the scope of the annexed claims.

. I claim:

1. In an arrangement for jet perforating casing in oil wells or the like having a tubing arranged in the casing, an elongated carriage small enough in diameter to enable tangentially in the planerof it to be run into the well through said tubing to perforate the casing below the lower end of the tubing, a plurality of spaced apart shaped charges of explosive mounted in the carriage in a single vertical plane pointing in the same direction and positioned to have the proper stand-olf distance from the casing when the carriage is contacting the casing, a plurality of electromagnets mounted in said carriage in the plane of the Vaxes of the jets of said shaped charges and between said shaped charges for bringing said carriage in contact with the casing tangentially in the plane of the axes of the jets of said shaped chargesl and an electrically interconnected energizing and firing circuit for energizing said electromagnets and firing said shaped charges in sequence such that the electromagnets are energized before and during the ring of the shaped charges whereby said carriage is moved into and maintained in contact with the casing before and while said shaped charges are red.

2. ln an arrangement for perforating casing in oil wells or the like having a tubing arranged in the casing, an elongated carriage small enough in diameter to enable it to be run into the well through said tubing to perforate the casing below the lower end of the tubing, a plurality of spaced apart guns mounted in the carriage in a single vertical plane and pointing in the same direction, a plurality of spaced apart electromagnets mounted in said carriage inthe plane of the axes of said guns and between said guns for bringing said carriage into contact with the casing tangentially in the plane of the axes of said guns, and an electrically interconnected energizing and firing circuit for energizing said electromagnets and ring said guns in sequence such that the electromagnets are energized before and during the ring of the guns whereby said carriage is moved into and maintained in contact with the casing before and while said guns are fired.

References Cited in the le of this patent UNITED STATES PATENTS 1,388,363 Miller Aug. 23, 1921 2,210,125 Raymond et al Aug. 6, 1940 2,309,835 Fearon Feb. 2, 1943 2,317,238 Mennecier Apr. 30, 1943 2,336,819 Turechek Dec. 14, 1943 2,399,211 Davis et al. Apr. 30, 1946 2,494,256 Muskat et al Jan. l0, 1950 2,543,814 Thompson et al Mar. 6, 1951 2,587,244 Sweetman Feb. 26, 1952 2,616,370 Foster Nov. 4, 1952 

